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1.1. Components of this course

Monday morning
What is textual markup and why is it useful? What is XML? An exercise in document analysis; How are XML files created and edited? Basic structure of a TEI document. Using an XML editor to create a valid TEI document.
Monday afternoon
A closer look at the structure and basic components of a TEI document. The TEI class system. Using Roma to explore the TEI landscape. Making your own schema.
Tuesday morning
The TEI Header; bibliographies; Manuscript transcription and description; Links, pointers, and gaiji; linguistic analysis and interpretation; consultations

1.2. Components of this course (contd.)

Tuesday afternoon
Names of people and places; Digital facsimiles; using the image markup tool; consultations
Wednesday morning
Reviews of TEI applications at King's College and at Oxford; Introduction to XML support technologies such as XPath, XSLT, XQuery
Wednesday afternoon
Using the TEI XSL stylesheet family; using XSLT in Oxygen; tools for publishing and analysing a large corpus of TEI documents. Review and discussion.

1.3. Course Objectives

  1. Examine the concept of markup and XML encoding
  2. Provide hands-on experience in using TEI XML markup
  3. Introduce the TEI scheme, its assumptions, and its organization
  4. Survey the whole landscape of the TEI recommendations
  5. Demonstrate how the TEI scheme may be customized to particular needs
  6. Demonstrate some real world applications of the TEI scheme
  7. Provide routes into more detailed information for exploration at your leisure
  8. Provide opportunities for questions and discussions relating to your own encoding needs and priorities

2. What is markup?

In order to talk about texts, markup and encoding of texts, we need to understand what we mean by these basic concepts. When we talk about text encoding, what do we mean by a text? What is in a text and what assumptions do we make in reading them?

2.1. What's in a text?

2.2. What's in a text (2)?

2.3. What's in a text (3)?

2.4. The ontology of text

Where is the text?
  • in the shape of letters and their layout?
  • in the original from which this copy derives?
  • in the stories we read into it? or in its author's intentions?

A "text" is an abstraction, created by or for a community of readers. Markup encodes and makes concrete such abstractions.

2.5. Encoding of texts

  • Texts are more than sequences of encoded glyphs
    • They have structure and content
    • They also have multiple readings
  • Encoding, or markup, is a way of making these things explicit

Only that which is explicit can be reliably processed

2.6. Styles of markup

  • In the beginning there was procedural markup
    RED INK ON; print balance; RED INK OFF
  • which being generalised became descriptive markup <balance type='overdrawn'>some numbers</balance>
  • also known as encoding or annotation

descriptive markup allows for easier re-use of data

2.7. What's the point of markup?

  • To make explicit (to a machine) what is implicit (to a person)
  • To add value by supplying multiple annotations
  • To facilitate re-use of the same material
    • in different formats
    • in different contexts
    • by different users

It's (usually) more useful to markup what we think things are than what they look like

2.8. Separation of form and content

  • Presentational markup cares more about fonts and layout than meaning
  • Descriptive markup says what things are, and leaves the rendition of them for a separate step
  • Separating the form of something from its content makes its re-use more flexible
  • It also allows easy changes of presentation across a large number of documents

2.9. Markup as a scholarly activity

  • The application of markup to a document can be an intellectual activity
  • In deciding what markup to apply, and how this represents the original, one is undertaking the task of an editor
  • There is (almost) no such thing as neutral markup -- all of it involves interpretation
  • Markup can assist in answering research questions, and the deciding what markup is needed to enable such questions to be answered can be a research activity in itself
  • Good textual encoding is never as easy or quick as people would believe
  • Detailed document analysis is needed before encoding for the resulting markup to be useful

2.10. What does markup capture?

<hi rend="dropcap">H</hi>&amp;WYN;ÆT WE GARDE
<lb/>na in gear-dagum þeod-cyninga
<lb/>þrym gefrunon, hu ða æþelingas
<lb/>ellen fremedon. oft scyld scefing sceaþe
<lb/>þreatum, moneg<expan>um</expan> mægþum meodo-setl
</damage>teah ...
 <l>Hwæt! we Gar-dena in gear-dagum</l>
 <l>þeod-cyninga þrym gefrunon,</l>
 <l>hu ða æþelingas ellen fremedon,</l>
 <l>Oft Scyld Scefing sceaþena þreatum,</l>
 <l>monegum mægþum meodo-setla ofteah;</l>
 <l>egsode Eorle, syððan ærest wearþ</l>
 <l>feasceaft funden...</l>

2.11. A useful mental exercise

Imagine you are going to markup several thousand pages of complex material....
  • Which features are you going to markup?
  • Why are you choosing to markup this feature?
  • How reliably and consistently can you do this?

Now, imagine your budget has been halved. Repeat the exercise!

3. XML (and friends)

Extensible Markup Language (XML) is a simple, very flexible text format derived from SGML (ISO 8879). Originally designed to meet the challenges of large-scale electronic publishing, XML is also playing an increasingly important role in the exchange of a wide variety of data on the Web and elsewhere.

3.1. Some alphabet soup

SGML Standard Generalized Markup Language
HTML Hypertext Markup Language
W3C World Wide Web Consortium
XML eXtensible Markup Language
DTD Document Type Definition (or Declaration)
CSS Cascading Style Sheet
Xpath XML Path Language
XSLT eXtensible Stylesheet Language - Transformations
XQuery XML Querying
RELAXNG Regular Expression Language for XML (New Generation)

Oh, and then there's also TEI, the Text Encoding Initiative

3.2. XML: what it is and why you should care

  • XML is structured data represented as strings of text
  • XML looks like HTML, except that:-
    • XML is extensible
    • XML must be well-formed
    • XML can be validated
  • XML is application-, platform-, and vendor- independent
  • XML empowers the content provider and facilitates data integration

3.3. XML terminology

An XML document may contain:-
  • elements, possibly bearing attributes
  • processing instructions
  • comments
  • entity references
  • marked sections (CDATA, IGNORE, INCLUDE)

An XML document must be well-formed and may be valid

3.4. XML syntax

<?xml version="1.0"?> <root> <elementName attributeName="attributeValue"> elementContent </elementName> <!-- this is a comment --> </root>

3.5. The rules of the XML Game

  • An XML document represents a (kind of) tree
  • It has a single root and many nodes
  • Each node can be
    • a subtree
    • a single element (possibly bearing some attributes)
    • a string of character data
  • Each element has a name or generic identifier
  • Attribute names are predefined for a given element; values can also be constrained

3.6. Representing an XML tree

  • An XML document is encoded as a linear string of characters
  • It begins with a special processing instruction
  • Element occurrences are marked by start- and end-tags
  • The characters < and & are Magic and must always be "escaped" if you want to use them as themselves
  • Comments are delimited by <!- - and - ->
  • CDATA sections are delimited by <![CDATA[ and ]]>
  • Attribute name/value pairs are supplied on the start-tag and may be given in any order
  • Entity references are delimited by & and ;

3.7. A complete XML document

<?xml version="1.0"?> <greetings xmlns="http://www.example.com/ns"> <hello type="fulsome">hello world!</hello> </greetings>
  • The XML declaration
  • Namespace declaration
  • The root element of the document itself
  • Other elements and content
  • Attribute and value

3.8. The XML declaration

<?xml version="1.0" encoding="iso-8859-1"?>
An XML document must begin with an XML declaration which does two things:
  • specifies that this is an XML document, and which version of the XML standard it follows
  • may specify a different character encoding for the document — if the default, and recommended, encoding UTF-8 is not being used

3.9. Namespace declarations

An XML document may can include elements declared in different name spaces.

<TEI xmlns="http://www.tei-c.org/ns/1.0" xmlns:math="http://www.mathml.org"> <p>...<math:expr>...</math:expr>...</p>...</TEI>
  • a namespace declaration associates a namespace prefix with an external URI-like identifier
  • the default namespace may be declared using a xmlns
  • other name spaces must all use a specially declared prefix
  • All TEI documents are declared within the TEI namespace
  • The xml namespace is available in all XML documents; TEI uses it for global attributes xml:id and xml:lang

3.10. The Doctype Declaration

You may sometimes find an optional "Document Type" declaration:

<?xml version="1.0" ?> <!DOCTYPE greeting SYSTEM "greeting.dtd []">
  • The DTD is one way of associating the document with its schema (but is not used by W3C or RELAXNG for this purpose)
  • The DTD subset is used to provide declarations additional to those in the schema, for example for external files
  • The DTD subset may be internal, external, or both

DTDs are now considered old-fashioned -- RELAXNG or W3C schemas are preferred.

3.11. The Tempest

<?xml version="1.0" encoding="utf-8" ?>
<div n="1">
 <head>SCENE I. On a ship at sea: a tempestuous noise of thunder and lightning heard.</head>
 <stage>Enter a Master and a Boatswain</stage>
  <ab>Here, master: what cheer?</ab>
  <ab>Good, speak to the mariners: fall to't, yarely,</ab>
  <ab>or we run ourselves aground: bestir, bestir.</ab>

3.12. Example deconstructed: root node

<?xml version="1.0" encoding="utf-8" ?>

<div n="1">
<!-- .... -->

3.13. Example deconstructed: head

<head>SCENE I. On a ship at sea: a tempestuous noise of thunder and lightning heard.</head>

3.14. Example deconstructed: stage direction and speech

<stage>Enter a Master and a Boatswain</stage>

3.15. An XML Tree For The Tempest

3.16. XML syntax: the small print

What does it mean to be well-formed?

  1. there is a single root node containing the whole of an XML document
  2. each subtree is properly nested within the root node
  3. names are always case sensitive
  4. start-tags and end-tags are always mandatory (except that a combined start-and-end tag may be used for empty nodes)
  5. attribute values are always quoted

Note: You can be valid in addition to being well-formed. This means you obey the rules of a specified schema, such as the TEI.

3.17. Test your XML knowledge

  • Which are correct?
    • <seg>some text</seg>
    • <seg><foo>some</foo> <bar>text</bar></seg>
    • <seg><foo>some <bar></foo> text</bar></seg>
    • <seg type="text">some text</seg>
    • <seg type='text'>some text</seg>
    • <seg type=text>some text</seg>
    • <seg type = "text">some text</seg>
    • <seg type="text">some text<seg/>
    • <seg type="text">some text<gap/></seg>
    • <seg type="text">some text< /seg>
    • <seg type="text">some text</Seg>

Date: 2008-07-13
Copyright University of Oxford